JPH07230775A - Transparent conductive film for electric field shield - Google Patents

Abstract

PURPOSE:To improve permeability and moisture proof with a sufficiently low surface resistance value provided in an electric field shield effect, by forming an ITO dispersed silicate film, ATO dispersed silicate film and an overcoat silicate film on a glass substrate. CONSTITUTION:An ITO dispersed silicate film of 0.07 to 0.60mum film thickness of dispersing in a silicate matrix an indium tin oxide grain with 1 to 15wt.% tin solid solved in an In2O3 compound by SnO2 conversion, ATO dispersed silicate film of 0.07 to 0.60mum film thickness of dispersing in a silicate matrix an antimony oxide tin grain with 1 to 20wt.% Sb doped in an SnO2 compound by Sb2O3 conversion and an overcoat silicate film formed of a transparent silicate glass layer in 0.08mum or more film thickness are laminated on a glass substrate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transparent conductive film for imparting an electric field shield effect to a front glass of a cathode ray tube such as a display of OA equipment and a cathode ray tube of a television.

[0002]

2. Description of the Related Art On the surface of a television cathode ray tube,
It has been known for a long time that antistatic treatment is performed because dust due to electrostatic charging is apt to adhere, and when a human body comes into contact with it, it discharges and receives an electric shock. In particular, due to the recent automation of office automation (OA), many OA devices have been introduced into offices, and it is not uncommon for the environment to face the display of the OA device and work all day. For this reason, the cathode ray tube (CRT) of a computer is not limited to dust adhesion on the surface of the CRT caused by static electricity, electric shock shock, the display screen is easy to see, and there is no visual fatigue. It is required to clear the safety standard so that it does not affect

In order to meet the above requirements, the present inventors have a two-layer structure having a surface resistance of 10 ⁵ Ω / □ or less, a total light transmittance of 93% or more and a haze value of 5% or less, and a 550 nm integrated reflectance of 10% or less. Invented and filed a transparent conductive film (Patent application 5
-44548). The transparent conductive film is a two-layer laminated structure of an ITO-dispersed silicate film and an overcoat, and is formed on a glass substrate with the ITO-dispersed silicate film as the first layer and the overcoat as the second layer. Therefore, the ITO dispersed silicate film is
It is a film in which O particles are dispersed in a silicate matrix, has a film thickness of 0.07 to 0.60 μm, and ITO particles have a particle volume of 50% or less and a particle volume fraction of 50%.
Including the above, the volume ratio of the ITO particles to the film volume is 35 to 95%, and the overcoat is 0.08 μm.
It is a transparent silicate glass layer having a thickness of m or more.

[0004]

However, depending on the environment in which the CRT is used, it is necessary for the film quality to withstand high temperature and high humidity. ITO fine particles are relatively weak against moisture,
Therefore, the surface resistance value of the absorbed transparent conductive film increases. In the above-mentioned two-layer film, the moisture penetrating into the overcoat film may deteriorate the ITO particles in the first layer, which may cause a problem in moisture resistance and aging of the transparent conductive film. Although the influence of moisture can be avoided by increasing the thickness of the overcoat film, the thickness of the overcoat film is usually controlled to a thin optical non-reflective film thickness of about 0.1 μm in order to reduce the reflectance. It is difficult to thicken this.

The object of the present invention, when applied to a CRT front glass, has a low surface resistance value sufficient for an electric field shielding effect and optical characteristics of a low haze and a high transmittance, and further has an antireflection effect and a moisture resistance. It is to provide a transparent conductive film having excellent properties.

[0006]

In order to achieve the above object, the present invention provides a glass substrate on which a first layer is an ITO-dispersed silicate film, a second layer is an ATO-dispersed silicate film, and a third layer is an overcoat silicate film. A transparent conductive film for electric field shield comprising a three-layer stack of films, wherein the first layer of the ITO-dispersed silicate film is a film in which fine particles of indium tin oxide are dispersed in a silicate matrix, and is 0.07 to 0.60.
The ATO-dispersed silicate film of the second layer having a thickness of μm is a film in which antimony tin oxide fine particles are dispersed in a silicate matrix, has a thickness of 0.07 to 0.60 μm, and has a third layer. The overcoat silicate film of.
A transparent conductive film for electric field shield, which is a transparent silicate glass layer having a thickness of 08 μm or more,

Alternatively, the first layer is ITO on the glass substrate.
Dispersed silicate film, second layer is silicate film, third layer is A
A transparent conductive film for electric field shield comprising a TO-dispersed silicate film, a fourth layer of which is a four-layer laminated structure of an overcoat silicate film, wherein the ITO-dispersed silicate film of the first layer comprises indium tin oxide fine particles dispersed in a silicate matrix. A film having a thickness of 0.07 to 0.60 μm, and the third layer of the ATO-dispersed silicate film is a film in which antimony tin oxide fine particles are dispersed in a silicate matrix,
A transparent conductive film for an electric field shield having a film thickness of 0.07 to 0.60 μm, wherein the second and fourth silicate films are transparent silicate glass layers having a thickness of 0.08 μm or more. A membrane.

Here, the indium tin oxide (ITO) fine particles are those in which tin is dissolved in a diindium trioxide compound in an amount of 1 to 15% by weight in terms of tin dioxide, and antimony tin oxide (ATO) fine particles. Is a tin dioxide compound doped with 1 to 20% by weight of antimony in terms of diantimony trioxide.

A film having such a three-layer or four-layer structure can be manufactured by the ink method as follows. First, as the film of the first layer, an ITO dispersed ink in which ITO fine particles are dispersed in silica sol and a solvent is applied to the surface of a CRT and dried to form a film by utilizing a polymerization reaction of silica sol. For example, a dispersant such as N-methyl-2-pyrrolidone (NMP) and N, N-dimethylformamide (DM
The ITO fine particle powder is sufficiently and uniformly mixed and dispersed in a dispersion solvent such as F) or ethanol, while an alkyl silicate solution as a binder is prepared, and both are mixed. The alkyl silicate is used to bond and fix the ITO powder on the glass surface. For example, orthomethyl silicate S
i (OCH ₃ ) ₄ , orthoethyl silicate Si (OC
₂ H ₅ ) ₄ or the like, or a form in which these are hydrolyzed to allow dehydration polycondensation to proceed to some extent is used. The alkyl silicate solution is prepared by diluting this with diacetone alcohol and adding a small amount of water or hydrochloric acid. IT
The O dispersion solution and the alkyl silicate solution are mixed to form ITO
Dispersed ink, which is, for example, by spin coating,
By dropping on the surface of the CRT front glass rotating at 100 to 200 rpm, the first layer of the ITO dispersed silicate film can be formed. The film forming method may be any method other than the spin coating method, such as the spray coating method and the dip coating method, as long as the method can uniformly and thinly spread the ink on the glass surface. In order to obtain a film having sufficient transparency and conductivity, ITO ultrafine powder having a particle size as small as possible, preferably 50 nm or less, is required. For example, such powder is sold and supplied by Sumitomo Metal Mining Co., Ltd.

For the ATO-dispersed silicate film, the same thing may be performed by changing the ITO fine particles to ATO fine particles. That is, an ATO dispersion obtained by mixing and dispersing ATO fine particle powder in an NMP dispersant or an ethanol dispersion solvent is, for example, an ethyl silicate solution obtained by adding diacetone alcohol or a small amount of water and hydrochloric acid to orthoethyl silicate Si (OC ₂ H ₅ ) _4. To form an ATO dispersion ink. ATO
A second layer of the ATO-dispersed silicate film can be formed by dropping the dispersion ink on the surface of the CRT front glass on which the first layer, which rotates at 100 to 200 rpm, is formed. Here, finer ATO fine particles are also preferable, but generally, ATO powder having a particle size of 10 nm or less can be relatively easily obtained from commercial products.

A silicate film such as an overcoat can also be formed by utilizing the polycondensation reaction of a silicate sol-gel solution. The silicate sol-gel solution is essentially the same as the alkyl silicate solution contained in the ITO dispersed silicate solution or the ATO dispersed silicate solution. That is, orthomethyl silicate Si (OCH ₃ ) ₄ , orthoethyl silicate Si
An alkyl silicate such as (OC ₂ H ₅ ) ₄ or an alkyl silicate in a form in which these are hydrodispersed to allow dehydration polycondensation to proceed to some extent is diluted with diacetone alcohol or the like, and a small amount of water or hydrochloric acid is further added. It is a thing. The silicate sol-gel ink is, for example, 100 to 200 rpm
The silicate film as the second layer or the fourth layer can be formed by dropping on the surface of the CRT front glass that rotates in the.

After the multilayer film is formed by a method such as the spin coating method as described above, this is baked to complete the film structure. The film baking temperature is 200 to 300 ° C. when the sol drying is completed for the front glass alone before CRT glass sealing.
Normally, the CRT finished spheres that can be fired as described above must be fired at a temperature of 200 ° C. or lower, but in this case, the shrinkage and conductivity of the sol are rather low.

[0013]

The ITO fine particles used in the first layer of the ITO-dispersed silicate film are transparent and have high conductivity, and if the filling rate with respect to the film volume is 35% or more, 0.07-
With a film thickness of 0.60 μm, a surface resistance of 10 ⁴ Ω / □ or less, which is effective for electric field shielding, can be realized. The film thickness of 0.07 to 0.60 μm is 0.0
This is because if it is less than 7 μm, sufficient conductivity cannot be obtained,
This is because if it exceeds 0.60 μm, the haze becomes 5% or more. The same applies to the ATO dispersed silicate film.

AT used for ATO dispersed silicate film
O fine particles also have transparent conductivity similar to ITO fine particles,
The level of conductivity obtained as a film is 1 digit in surface resistance value.
Since it is three orders of magnitude lower, this film alone cannot be used as an electric field shield. On the other hand, ATO fine particles do not increase the resistance value due to moisture, so in terms of moisture resistance ITO
Better. The refractive index of the ATO dispersed silicate film is I
Similar to the TO-dispersed silicate film, it has a high value of 1.60 to 1.78, and when combined with an overcoat silicate film having a refractive index of about 1.46, a sufficient reflectance reduction effect can be provided. Further, the combination of the ITO dispersion film and the ATO dispersion film, each of which has conductivity, also improves the electric field shielding effect of the film as a whole.

The ITO-dispersed silicate film and the ATO-dispersed silicate film may be laminated as they are, but the reflectance can be further reduced by inserting a silicate film between them. Further, although it depends on the solvent composition of the ink, ITO and ATO generally have different dispersion solvents. Therefore, by adjusting both with a solvent used for the silicate ink between them, it is possible to enhance the adhesiveness at the interface between the films. .

[0016]

EXAMPLES Examples of the present invention will be shown below. The film thickness and the refractive index of the formed film were measured by an ellipsometer manufactured by Mizojiri Optical Co., Ltd. The surface resistance is 1 on the ITO dispersed silicate film.
The measurement was carried out by baking a 00 mm × 5 mm Ag paste at intervals of 100 mm. The haze value and the transmittance were measured using a haze meter HR-200 manufactured by Murakami Color Research Laboratory.
The reflectance was measured using a Shimadzu spectrophotometer. (Example 1) Specific surface area 27.5 cm ² , average particle size 25.
15 g of ITO ultrafine powder (ITO-UFP) manufactured by Sumitomo Metal Mining Co., Ltd., 3 nm (evaluated by a transmission electron microscope), N
20 g of methyl-2-pyrrolidone (NMP), N, N
7 g of dimethylformamide (DMF) and 70 g of 4-hydroxy-4-methyl-2-pentanone (diacetone alcohol) were mixed well to prepare an ITO dispersion solution. Subsequently, the specific surface area was 33.4 cm ² , and the average particle size was 9.3.
nm (evaluated with a transmission electron microscope), Sumitomo Metal Mining Co., Ltd.
An ATO dispersion solution was prepared in exactly the same manner by using ATO ultrafine powder. On the other hand, while stirring a mixed solution of 1.5 g of ethyl silicate 40 manufactured by Tama Chemical Industry Co., Ltd. having an average degree of polymerization of 4 to 5 and 16 g of diacetone alcohol and 1.5 g of distilled water, 3 g of 5% hydrochloric acid aqueous solution and diacetone. Alcohol 2
g, a mixed solution of 2.4 g of distilled water was added dropwise to prepare an ethyl silicate solution. Next, two liquids of the ITO dispersion solution and the ethyl silicate solution were mixed and added dropwise from a beaker onto a 200 × 200 × 3 mm plate glass rotating at 150 rpm. This is baked in air at a firing temperature of 170 ° C for 30
After baking for a minute, screen print Ag paste to 15
An electrode was formed by baking at 0 ° C. for 30 minutes. Then again 150r
The mixed solution of the ATO dispersion solution and the ethyl silicate solution was dropped while rotating at pm, and 1 minute later, the ethyl silicate solution alone was dropped from a beaker.

The plate glass thus spin-coated with the three-layer film was baked in the air at a baking temperature of 170 ° C. for 30 minutes. The surface resistance value, haze, film thickness, and reflectance of the formed film immediately after firing were measured, and the surface resistance value was measured after holding the film at 80 ° C. and 95% humidity for 400 hours. The results of these measurements are shown in Table 1. The resistance value was in the order of 10 ⁴ Ω / □ suitable for the electric field shield, and the optical characteristics such as haze and reflectance were also acceptable values for CRT.
Further, there was no deterioration of the resistance value after the moisture resistance test, and a three-layer film structure having sufficient moisture resistance was obtained.

(Embodiment 2) In the same manner as in Embodiment 1, 3
The layer laminated film was spin-coated on a plate glass and baked. However, the firing temperature was 300 ° C. for both times. As for the characteristics of the formed film, as shown in Table 1, the resistance value was lower than that at 170 ° C. firing.

Example 3 An ITO dispersion, an ATO dispersion, and an ethyl silicate solution were prepared in the same manner as in Example 1 and then rotated at 150 rpm 200 × 200 × 3 mm.
A mixed solution of the ITO dispersion solution and the ethyl silicate solution was dropped from a beaker on the plate glass of No. 1 as a first layer, and the mixture was placed in the atmosphere to
After baking at 70 ° C. for 30 minutes to form an Ag electrode, the second layer is the ethyl silicate solution alone, the third layer is the mixed solution of the ATO dispersion solution and the ethyl silicate solution, and the fourth layer is the ethyl silicate solution. The individual films were formed at intervals of 1 minute. The plate glass thus spin-coated with a four-layer film was baked at 170 ° C. in the air.
It was baked for 30 minutes. The characteristics of the formed film are shown in Table 1.

(Embodiment 4) In the same manner as in Embodiment 3, 4
The layer laminated film was spin-coated on a plate glass and baked. However, the firing temperature was 300 ° C. The characteristics of the formed film are shown in Table 1.

(Comparative Example 1) In the same manner as in Example 1, 1% of the mixed solution of the ITO dispersion solution and the ethyl silicate solution was used for the first layer.
After forming a film on a plate glass of 200 × 200 × 3 mm rotating at 50 rpm and baking at 170 ° C. for 30 minutes to form an Ag electrode, a single solution of ethyl silicate as a second layer is dropped from a beaker and heated at 170 ° C. for 30 minutes. Minutes were fired. As for the characteristics of the formed film, it is understood that the reflectance is higher than that of the examples of the present invention, the resistance value after the humidity resistance test is significantly increased, and the moisture resistance is poor.

(Comparative Example 2) Just as in Comparative Example 1, 2
The layer laminated film was spin-coated on plate glass and baked. However, the baking temperature was 300.degree. C. for 30 minutes both times. The characteristics of the formed film are shown in Table 1. Initial resistance value is Comparative Example 1
Although slightly lower than the above, deterioration due to the moisture resistance test is observed.

[0023]

[Table 1]

[0024]

According to the present invention, a film having a low surface resistance value, a high transmittance and a low haze can be obtained, and since this film is excellent in moisture resistance, it is unlikely to deteriorate with time, and can be used as a vapor deposition film or the like. Because it is overwhelmingly advantageous in cost compared to CR
It is very suitable for the electric field shield on the T front surface.

Claims (2)

[Claims] 1. A transparent conductive film for electric field shield, comprising a glass substrate, a first layer of which is an ITO-dispersed silicate film, a second layer of which is an ATO-dispersed silicate film, and a third layer of which is an overcoat silicate film. The first layer of the ITO-dispersed silicate film is a film in which fine particles of indium tin oxide are dispersed in a silicate matrix and has a thickness of 0.07 to 0.60 μm. Is a film in which fine particles of antimony tin oxide are dispersed in a silicate matrix and has a film thickness of 0.07 to 0.60 μm. The overcoat silicate film of the third layer is 0.08 μm.
A transparent conductive film for an electric field shield, which is a transparent silicate glass layer having the above thickness. 2. An electric field comprising a glass substrate on which a first layer is an ITO-dispersed silicate film, a second layer is a silicate film, a third layer is an ATO-dispersed silicate film, and a fourth layer is an overcoat silicate film. In the transparent conductive film for shielding, the first layer of the ITO-dispersed silicate film is a film in which indium tin oxide fine particles are dispersed in a silicate matrix, and has a film thickness of 0.07 to 0.60 μm. The three-layer ATO-dispersed silicate film is a film in which antimony tin oxide fine particles are dispersed in a silicate matrix, has a film thickness of 0.07 to 0.60 μm, and the second and fourth silicate films are A transparent conductive film for an electric field shield, which is a transparent silicate glass layer having a thickness of 0.08 μm or more.